Calderón preconditioning techniques for integral equation based methods

Some recent advances in the Calderón preconditioning techniques for integral-equation-based methods are discussed in this paper. Four different techniques are presented briefly: a low-frequency Calderón preconditioner for the electric-field integral equation (EFIE) in analyzing perfect electric conductor (PEC) problems, an augmented EFIE (AEFIE) with Calderón preconditioner for simulating electrically large problems, several Calderón-type preconditioners for the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) equations, and the derivation of N-Müller equations using Calderón identities. A number of numerical examples are given to demonstrate the performance of the proposed approaches.